TY - JOUR A1 - Schneider, Ingo T1 - Microbiological and Enzymatic Inverstigations of soils in the Rustenburg Mining Area N2 - In soils of the Rustenbug Minig Area microorganism concentration and activity of several enzymes (dehydrogenase, phosphatase, protease, amylase, cellulase, xylanase) were determined. First results indicate an increase of heavy metal resistant Microorganisms and a possible inhibition of carbohydrate degrading enzymes. Y1 - 2001 ER - TY - JOUR A1 - Wacker, Alexander A1 - von Elert, Eric T1 - Polyunsaturated fatty acids : evidence for non-substitutable biochemical resources in daphnia galeata N2 - The factors that determine the efficiency of energy transfer in aquatic food webs have been investigated for many decades. The plant-animal interface is the most variable and least predictable of all levels in the food web. In order to study determinants of food quality in a large lake and to test the recently proposed central importance of the long-chained eicosapentaenoic acid (EPA) at the pelagic producer-grazer interface, we tested the importance of polyunsaturated fatty acids (PUFAs) at the pelagic producer-consumer interface by correlating sestonic food parameters with somatic growth rates of a clone of Daphnia galeata. Daphnia growth rates were obtained from standardized laboratory experiments spanning one season with Daphnia feeding on natural seston from Lake Constance, a large pre-alpine lake. Somatic growth rates were fitted to sestonic parameters by using a saturation function. A moderate amount of variation was explained when the model included the elemental parameters carbon (r2 = 0.6) and nitrogen (r2 = 0.71). A tighter fit was obtained when sestonic phosphorus was incorporated (r2 = 0.86). The nonlinear regression with EPA was relatively weak (r2 = 0.77), whereas the highest degree of variance was explained by three C18-PUFAs. The best (r2 = 0.95), and only significant, correlation of Daphnia's growth was found with the C18-PUFA a-linolenic acid (a-LA; C18:3n-3). This correlation was weakest in late August when C:P values increased to 300, suggesting that mineral and PUFA- limitation of Daphnia's growth changed seasonally. Sestonic phosphorus and some PUFAs showed not only tight correlations with growth, but also with sestonic alpha-LA content. We computed Monte Carlo simulations to test whether the observed effects of alpha-LA on growth could be accounted for by EPA, phosphorus, or one of the two C18-PUFAs, stearidonic acid (C18:4n-3) and linoleic acid (C18:2n-6). With >99% probability, the correlation of growth with alpha-LA could not be explained by any of these parameters. In order to test for EPA limitation of Daphnia's growth, in parallel with experiments on pure seston, growth was determined on seston supplemented with chemostat-grown, Plimited Stephanodiscus hantzschii, which is rich in EPA. Although supplementation increased the EPA content 80-800x, no significant changes in the nonlinear regression of the growth rates with alpha-LA were found, indicating that growth of Daphnia on pure seston was not EPA limited. This indicates that the two fatty acids, EPA and alpha-LA, were not mutually substitutable biochemical resources and points to different physiological functions of these two PUFAs. These results support the PUFA-limitation hypothesis for sestonic C:P < 300 but are contrary to the hypothesis of a general importance of EPA, since no evidence for EPA limitation was found. It is suggested that the resource ratios of EPA and alpha-LA rather than the absolute concentrations determine which of the two resources is limiting growth. Y1 - 2001 UR - http://www.esajournals.org/esaonline/?request=get-abstract&issn=0012-9658&volume=082&issue=09&page=2507 ER - TY - JOUR A1 - Fischer, Markus T1 - The role of vegetative spread and seed dispersal for optimal life histories of clonal plants : a simulation study Y1 - 2001 ER - TY - JOUR A1 - Fischer, Markus A1 - Müller-Schärer, H. T1 - Genetic structure of the annual weed Senecio vulgaris in relation to habitat type and population size Y1 - 2001 ER - TY - JOUR A1 - Fischer, Markus A1 - Kéry, M. A1 - Matthies, D. T1 - The effect of plant population size on the interactions between the rare plant Gentiana cruciata and its specialized herbivore Maculinea rebeli Y1 - 2001 ER - TY - JOUR A1 - Pecher, Gabriele A1 - Spahn, Gunter A1 - Schirrmann, Thomas A1 - Kulbe, Hagen A1 - Ziegner, Maja A1 - Schenk, Jörg A. A1 - Sandig, Volker T1 - Mucin gene (MUC1) transfer into human dendritic cells by cationic liposomes and recombinant adenovirus N2 - BACKGROUND: Dendritic cells (DC) as antigen presenting cells play an important role in immunotherapy of cancer. Mucin, encoded by the gene MUC1, is a human tumor antigen expressed in breast, pancreatic and ovarian cancers. Therefore, MUC1-transfected DC would be an attractive tool in constructing cancer vaccines. MATERIALS AND METHODS: Using two different cationic liposome preparations and, for comparison, a recombinant adenovirus expressing mucin, we tested the efficiency of mucin gene transfer into DC by flow cytometry. We investigated if these transfected DC were able to specifically stimulate autologous peripheral blood lymphocytes (PBL) from healthy donors. RESULTS: Flow cytometry revealed that 5-20% of DC transfected with liposomes Lipofectin and 20-40% of DC transduced with adenovirus expressed the relevant mucin epitopes. The expression of mucin on DC was similar to the expression of mucin found on carcinoma cells. After antigen uptake, DC specifically stimulated autologous PBL. CONCLUSION: We have shown that cationic liposomal gene transfer into human DC was feasible. We could obtain antigen specific stimulation of PBL at a similar rate as with adenoviral MUC1-transduced DC. Y1 - 2001 SN - 0250-7005 ER - TY - JOUR A1 - Pecher, Gabriele A1 - Harnack, U. A1 - Gunther, M. A1 - Hummel, M. A1 - Fichtner, I. A1 - Schenk, Jörg A. T1 - Generation of an immortalized human CD4+ T cell clone inhibiting tumor growth in mice. N2 - Tumor antigen-specific T cell clones represent a useful tool in tumor immunology; however, their long-term culture is limited. To generate an immortalized cytotoxic T cell clone against the human tumor antigen mucin, we exposed a previously generated T cell culture to Herpesvirus saimiri. We obtained an immortalized human CD4+ T cell clone, termed SITAM. Clonality of these cells was shown by analysis of the alpha/beta-T cell receptor (TCR) repertoire. Cytolytic activity was demonstrated against several mucin-expressing tumor cell lines and could not be detected against non-mucin-expressing cells. SITAM cells maintained their features stably for 2 years. Furthermore, growth of the tumor cell line Capan-2 in NOD/SCID mice was inhibited when SITAM cells were coinjected subcutaneously with tumor cells. SITAM cells provide an unlimited source of clonal T cells for analysis of tumor recognition and may be of help in TCR-targeted immunotherapy. Y1 - 2001 UR - http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6WBK-45S4JD7- VM&_coverDate=05%2F18%2F2001&_alid=268965202&_rdoc=1&_fmt=&_orig=search&_qd=1&_cdi=6713&_sort=d&view=c&_acct=C000053886&_ v ER - TY - JOUR A1 - Bergholz, André A1 - Heymann, Stephan A1 - Schenk, Jörg A. A1 - Freytag, Johann Christoph T1 - Biological sequences integrated: a relational database approach N2 - Over the last decade the modeling and the storage of biological data has been a topic of wide interest for scientists dealing with biological and biomedical research. Currently most data is still stored in text files which leads to data redundancies and file chaos. In this paper we show how to use relational modeling techniques and relational database technology for modeling and storing biological sequence data, i.e. for data maintained in collections like EMBL or SWISS-PROT to better serve the needs for these application domains. For this reason we propose a two step approach. First, we model the structure (and therefore the meaning of the) data using an Entity-Relationship approach. The ER model leads to a clean design of a relational database schema for storing and retrieving the DNA and protein data extracted from various sources. Our approach provides the clean basis for building complex biological applications that are more amenable to changes and software ports than their file-base counterparts. Y1 - 2001 UR - http://www.springerlink.com/app/home/ contribution.asp?wasp=161c4c19086a4dceac9312b46e5f2348&referrer=parent&backto=issue,1,5;journal,14,29;linkingpublicationr esults,1:102835,1 ER - TY - JOUR A1 - Fischer, Markus T1 - Landscape dynamics can accelerate metapopulation extinction Y1 - 2001 ER - TY - JOUR A1 - Gzik, Axel T1 - Uptake, transport and effects of heavy metals in higher plants Y1 - 2001 ER -